A sonic-type boom prompted a flood of calls to area agencies from curious residents, but officials were at a loss for answers.
The sound might have been responsible for breaking a window at downtown’s First Interstate Bank building.
A member of the building’s management who would only identify herself as Kathy said a window broke at about the same time the boom occurred but said management thought it was coincidental. She said she had no idea what caused the break.
The most calls came from East County, but many came from downtown as well, officials said.
Bob Finn, a spokesman for Caltech in Pasadena, said the center received many calls about the sound but said “it is definitely not an earthquake.”
Dan Atkins of the U.S. Weather Service in San Diego said the sound had nothing to do with weather.
Senior Chief Petty Officer Bob Howard, a Navy spokesman, said the Navy is investigating the cause too.
“We have checked with some of our subordinate commands, but none of them have said they were responsible,” Howard said. “We don’t know if it was a military aircraft or a military site that could have been involved.
“It is very easy to point at the military, since we have all the large equipment that can produce such a large noise.”